1. Field
The present disclosure relates generally to power converters, and, more specifically, the present disclosure relates to controllers for power converters.
2. Related Art
Power converters are used in many electrical devices to transform an alternating current (ac) power supply into a direct current (dc) power supply. Generally, these converters include a controller that switches a power switch between an ON state and an OFF state to control the amount of power transmitted to the output of the converter.
In some devices, the controller may be included within an integrated circuit and may use comparators, operational amplifiers, and similar circuits to perform various functions. These analog and digital circuits generally rely on differences in currents, referred to as bias currents, to operate. The magnitudes of the bias currents influence the speed of the circuits. For instance, faster comparators typically require high bias currents, while slower comparators typically require lower bias currents. Similarly, high-bandwidth amplifiers typically require high bias currents, while low-bandwidth amplifiers typically require lower bias currents
At high loads, it may be desirable to have fast circuits, while at low loads, slower circuits may be acceptable. Conventional power converters typically supply a steady bias current having a magnitude sufficient to operate the circuits at the speeds required at high loads. While supplying bias currents in this manner allows the circuits to operate at sufficient speeds at both light load and high load conditions, power is wasted at light load conditions where low power consumption is very important.